1. Field of the Invention
The present invention relates to a capacitive touch panel, and, more particularly, to methods, systems, and apparatuses for providing reduced waveform distortion for a touch panel sensor.
2. Discussion of the Related Art
Input from a touch sensor may include a driving signal input through a capacitor positioned between a sensing electrode and a driving electrode of a touch panel, and a noise signal input through a capacitor positioned between a sensing node of the touch panel and an object (e.g., a finger) touching the touch panel. A sensed signal from the touch sensor may be obtained by mixing the driving signal input and the noise signal input.
The sensed signal may be distorted by interference from external sources. For example, radiation may be caused by a fluorescent light or charging device in proximity to the touch sensor. In some cases, this interference may be sufficient to cause an amplifier (e.g., an operating amplifier) of an analog signal sensor of the touch sensor to operate outside of its normal operating range. Accordingly, this may result in the distortion of the output of the analog signal sensor of the touch sensor, which may in turn interfere with providing touch information from the touch sensor.
Capacitance of a feedback capacitor of an analog sensor may be increased or a high-order analog filter may be used in order to prevent an output signal of an amplifier of the analog sensor from being outside the normal operating range. However, these modifications typically result in an increased circuit area and additional power consumption.